1. Field of the Invention
This invention relates to a combustion temperature high speed detection device for detecting, at a high speed, the combustion gas temperature of a combustor, which is provided in a gas turbine system, based on a temperature detection signal from a temperature detector installed in the gas turbine system.
2. Description of the Related Art
A temperature detector using a thermocouple for detecting the combustion gas temperature of a combustor, which is provided in a gas turbine system, is installed in the gas turbine system. A temperature controller of the gas turbine system provides feedback on a temperature detection signal from the temperature detector to exercise control such that the combustion gas temperature of the combustor reaches a predetermined temperature desired value.
An example of temperature detection by a temperature detector using a thermocouple in an electric power plant is an in-piping fluid temperature measuring device as disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-183238). In Patent Document 1, a temperature detection element, which is a thermocouple, is connected to steam piping for connecting a steam generator and a steam turbine of a nuclear power plant, although this is not shown herein. The temperature detection element is connected to a temperature detector, an output signal of the temperature detector is entered into a temperature corrector, and an output signal of the temperature corrector is entered into a temperature monitor. The temperature corrector corrects the surface temperature of the piping based on a correlation between a premeasured piping surface temperature and an in-piping temperature, a saturated steam temperature found from a steam pressure, and a correlation between a premeasured steam pressure and the in-piping temperature, thereby determining the fluid temperature inside the piping. According to this procedure, temperature detection can be effected by mounting the temperature detection element on the surface of the piping, without using a thermowell (a protective tube for a thermometer).
With the gas turbine system, a lag in detection of the combustion gas temperature poses a problem. To detect the combustion gas temperature, it is desirable to provide the temperature detector at the outlet of the combustor through which a combustion gas is discharged. However, the temperature is so high at this position that there is no other choice but to place the temperature detector at a downstream side of the gas turbine. This leads to a lag in temperature detection. Furthermore, the combustion gas is high in temperature and high in flow velocity even at the downstream side of the gas turbine. Thus, the thermocouple of the temperature detector is accommodated in a protective material for the purpose of protection. This protective material constitutes a factor for a lag in detection of the combustion gas temperature.
In controlling the combustion gas temperature based on the temperature detection signal, therefore, high speed control responsive to a quick change in the combustion temperature is difficult. If the combustion temperature becomes too high, in particular, the combustor may be damaged. Thus, rapid temperature control is desired in response to a change in the temperature from a lower side to a higher side. In the current situation, high speed control responsive to a rapid temperature rise is difficult because of a lag in temperature detection. To reduce a lag in detection due to the protective material, efforts have been made to minimize the thickness of the protective material. However, the lag in detection has not been fully decreased. Under these circumstances, studies have been conducted on high speed detection of the combustion gas temperature by detection signal processing methods.